Changing of MAC/Physical address is salutary for following purposes:

1. If your Internet Service Provider (ISP) does mac binding with your id (Almost all do).
   So in case your old modem/router is no longer usable and If you want to use a new modem then it
   will result in authentication failure.


2. For "MAC Spoofing" : That is showing you have a different address to what you actually have.

The Steps are:

1.Telnet to your modem/router i.e

• Go to Command prompt and type telnet 192.168.1.1
  
• Enter your user name and press enter and then the password.

2. A menu will be displayed then type sh a # prompt appears .This lets you into the shell of your router/modem

3.Now to change your ethernet Interface's address you will have to first shut it down so for that
to happen you would have to connect through your usb interface .

4. To View what interfaces are available type ifconfig

5. Assuming that you want to change eth0 interface, type the following sequence of steps :

• ifconfig eth0 down

• ifconfig eth0 hw ether <your mac address>

For example: ifconfig eth0 hw ether 02:10:18:01:00:01

• ifconfig eth0 up

6. That should do it type Ifconfig eth0 to view the change to eth0 Interface.